65991215 has 4 divisors (see below), whose sum is σ = 79189464. Its totient is φ = 52792968.

The previous prime is 65991193. The next prime is 65991227. The reversal of 65991215 is 51219956.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 65991215 - 2⁶ = 65991151 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6599117 + ... + 6599126.

It is an arithmetic number, because the mean of its divisors is an integer number (19797366).

Almost surely, 2^65991215 is an apocalyptic number.

65991215 is a deficient number, since it is larger than the sum of its proper divisors (13198249).

65991215 is a wasteful number, since it uses less digits than its factorization.

65991215 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13198248.

The product of its digits is 24300, while the sum is 38.

The square root of 65991215 is about 8123.4977072687. The cubic root of 65991215 is about 404.1060708153.

The spelling of 65991215 in words is "sixty-five million, nine hundred ninety-one thousand, two hundred fifteen".